Semiconductor device and method for fabricating the same

Abstract

The present application discloses a semiconductor device and a method for fabricating the semiconductor device. The semiconductor device includes a substrate, a conductive feature comprising tungsten positioned above the substrate, a coverage layer comprising tungsten nitride positioned on a top surface of the conductive feature, and a plurality of capacitor structures positioned above the substrate.

What is claimed is: 
     
       1. A semiconductor device, comprising:
 a substrate; 
 a conductive feature comprising tungsten positioned above the substrate; 
 a coverage layer comprising tungsten nitride positioned on a top surface of the conductive feature; 
 a plurality of capacitor structures positioned above the substrate; and 
 a plurality of word lines positioned in the substrate and a doped region positioned between an adjacent pair of the plurality of word lines, wherein the conductive feature is positioned on the doped region. 
 
     
     
       2. The semiconductor device of  claim 1 , wherein the conductive feature is positioned below the plurality of capacitor structures. 
     
     
       3. The semiconductor device of  claim 1 , wherein the conductive feature is positioned above the plurality of capacitor structures. 
     
     
       4. The semiconductor device of  claim 1 , further comprising a plurality of isolation structures positioned in the substrate, wherein the plurality of isolation structures are separated from each other and define a plurality of active regions of the substrate. 
     
     
       5. The semiconductor device of  claim 4 , further comprising a doped region, wherein each of the plurality of active regions intersects two word lines, the doped region is positioned between one of the two word lines and one of the plurality of isolation structures, and the conductive feature is positioned on the doped region. 
     
     
       6. The semiconductor device of  claim 5 , wherein the two word lines extend along a first direction and the plurality of active regions extend along a direction that is slanted with respect to the first direction. 
     
     
       7. The semiconductor device of  claim 1 , further comprising a plurality of bit line contacts positioned above the substrate and a plurality of bit lines positioned above the substrate, wherein one of the plurality of bit line contacts is positioned on the coverage layer and is positioned under one of the plurality of bit lines. 
     
     
       8. The semiconductor device of  claim 7 , wherein the plurality of bit lines are formed as wavy lines. 
     
     
       9. The semiconductor device of  claim 1 , further comprising a plurality of bit lines positioned above the substrate, wherein the plurality of word lines extend along a first direction, the plurality of bit lines extend along a second direction, and the first direction is perpendicular to the second direction. 
     
     
       10. The semiconductor device of  claim 1 , wherein the plurality of capacitor structures comprise a plurality of bottom electrodes inwardly positioned above the substrate, a capacitor insulating layer positioned on the plurality of bottom electrodes, and a top electrode positioned on the capacitor insulating layer. 
     
     
       11. A method for fabricating a semiconductor device, comprising:
 providing a substrate; 
 forming a conductive feature comprising tungsten positioned above the substrate; and 
 forming a coverage layer comprising tungsten nitride positioned on a top surface of the conductive feature; and 
 cleaning the conductive feature before forming a coverage layer comprising tungsten nitride positioned on a top surface of the conductive feature, wherein cleaning the conductive feature comprises applying a reducing agent to the top surface of the conductive feature, and the reducing agent is titanium tetrachloride, tantalum tetrachloride, or a combination thereof. 
 
     
     
       12. The method for fabricating the semiconductor device of  claim 11 , further comprising forming a plurality of capacitor structures positioned above the substrate. 
     
     
       13. The method for fabricating the semiconductor device of  claim 12 , wherein the conductive feature is positioned below the plurality of capacitor structures. 
     
     
       14. The method for fabricating the semiconductor device of  claim 12 , wherein the conductive feature is positioned above the plurality of capacitor structures. 
     
     
       15. The method for fabricating the semiconductor device of  claim 12 , further comprising forming a plurality of word lines positioned in the substrate and a doped region positioned between an adjacent pair of the plurality of word lines, wherein the conductive feature is positioned on the doped region. 
     
     
       16. The method for fabricating the semiconductor device of  claim 12 , further comprising forming a plurality of bit line contacts and a plurality of bit lines, wherein one of the plurality of bit line contacts is positioned on the coverage layer and is positioned under one of the plurality of bit lines. 
     
     
       17. The method for fabricating the semiconductor device of  claim 16 , wherein the plurality of bit lines are formed as wavy lines. 
     
     
       18. The method for fabricating the semiconductor device of  claim 16 , wherein the plurality of capacitor structures comprise a plurality of bottom electrodes inwardly positioned above the substrate, a capacitor insulating layer positioned on the plurality of bottom electrodes, and a top electrode positioned on the capacitor insulating layer.